Fracturing process is widely used in oil and gas production for increasing production of oil well, prolonging high-production life of oil well, and exploiting undeveloped resources. In order to prevent underground fracturing fracture from closure, to retain oil and gas passages and to maintain fracture conductivity capacity, it is necessary to fill the fractures with a proppant. Due to the difference in depth of oil reservoir and in oil viscosity, the requirements for properties of proppants, such as strength, apparent density and particle size, are different. The fracturing proppants are divided into high-density and high-strength proppants, medium-density and high-strength proppants and low-density and high-strength proppants according to bulk density thereof. In recent years, requirements for proppants with a super-low density have appeared. At present, the fracturing proppants on market commonly have a particle size of 16-30 mesh (1180-600 μm), 20-40 mesh (850-425 μm), 30-50 mesh (600-300 μm), 40-60 mesh (425-250 μm), 40-70 mesh (425-212 μm), etc. However, no matter what kind and what specification a petroleum fracturing proppant is, it should have a relatively low apparent density on the premise of having a sufficient crushing resistance, so as to decrease the fracturing cost, guarantee fracture filling saturation and increase production of oil well.
Currently, petroleum fracturing proppants are generally produced with bauxite as main raw material, and one or more metal oxides, such as manganese oxide, calcium oxide, iron oxide, magnesium oxide and zircon, as a mineralizer. Chinese patent No. 02112746.8 discloses a fracturing proppant prepared from, as main raw materials, 45%-55% by weight of sintered bauxite, 10%-30% by weight of kaolin, and 20%-35% weight of red mud produced in Yixing. The above raw materials are pulverized, mixed, pelletized, and sintered to give the fracturing proppant. Chinese patent No. 93111983.9 discloses a fracturing proppant prepared by sintering and pulverizing 70%-90% of sintered bauxite as a main raw material, adding an auxiliary material composed of a multi-component oxide and soft clay for co-milling, adding water or an organic solvent for grinding, then debonding, palletizing, sieving, sintering, polishing and sieving again. Chinese patent No. 02157202.X discloses a fracturing proppant prepared by sintering 90%-94% of high-grade born bauxite and 6%-10% of manganese oxide ore powders at a high temperature of 1330° C.-1350° C. Chinese patent No. 02157202.X discloses a formula widely used in proppant production industry at present, but the fracturing proppant provided by the patent is prepared from high-quality resources such as special-grade or first-grade bauxite and MnO2 or manganese ore with a content of more than 50% at a relatively high temperature. Thus, high energy consumption and high resource consumption in the preparation process limit further development of fracturing proppants.